1. Field of the Invention
The present invention relates to a liquid crystal (LC) medium for polymerization alignment process and method for manufacturing a liquid crystal display (LCD) having the same, and more particularly, to a LC medium having inhibitor and method for manufacturing a LCD having the LC medium.
2. Description of the Prior Art
With progression of large size liquid crystal displays (LCDs), a requirement for wider viewing angle is confronted. Therefore multi-domain vertical alignment (MVA) LCD, which possesses advantages such as wider viewing angle and shorter response time, has become a mainstream of the large size LCDs.
In a conventional MVA LCD, a plurality of protrusion is utilized to make the liquid crystal (LC) molecules have a pre-tilt angle. Therefore processes such as thin film deposition, photolithography process, and etching process are needed to form the protrusions, and thus complexity and cost of the fabrication are increased. More serious, the protrusions shades light, reduces aperture ratio of the MVA LCD, and reduces brightness of the MVA LCD.
Therefore, polymerization alignment process is developed to provide polymers used to replace the protrusions and thus to make the LC molecules have the pre-tilt angle in the MVA LCD.
Reactive monomers used in the polymerization alignment process are monomers that can be triggered by light or heat, therefore the reactive monomers may polymerize in process before the polymerization alignment process. For instance, the reactive monomers are adapted to polymerize during an UV light curing process that is used to cure the sealant in advance of the polymerization alignment process. Consequently, the remnant reactive monomers are not sufficient to make the LC molecules have the pre-tilt angle in the polymerization alignment process. Meanwhile, phase separation due to the polymerization additionally affects stability of the LC medium before the polymerization alignment process. More seriously, optics anomaly defects such as mura or image sticking are created in the LCD. In addition, it is well known that the polymerization of the reactive monomers is triggered not only by light or heat in the UV light curing process, but it is also triggered by light from environment when the LCD is in a buffer area in advance of the polymerization alignment process.
To avoid problems described above, many solutions are provided such as providing an additional mask in the UV light curing process, thus light is obstructed from the LC medium. However, the additional mask consequentially increases cost. Furthermore, since the LC medium having reactive monomers is more sensitive than the conventional one, environmental light has to be precisely controlled in the whole LCD fabricating process in order to keep the LC medium from being affected, and to keep its stability. This shows that both cost and complexity of the fabricating process are increased with application of the polymerization alignment process and LC medium used in the polymerization alignment process.